1. Field of the Invention
The present invention relates to a power amplifier (power amplification circuit), and, for example, relates to a power amplifier suitable for use in a transmission power amplifier applied to communication terminal apparatuses, such as a mobile phone of a CDMA system etc.
2. Description of Related Art
The number of mobile phone subscribers in Japan of today is approximately 80% of the population. Among those, the number of owners of mobile communications terminal apparatuses using a CDMA (Code Division Multiple Access) technology reaches approximately 50%. As to demand for the terminals in the future, it is considered that the demand for mobile communications terminal apparatuses further increases as PDC (Personal Digital Cellular) terminal apparatuses etc. are replaced with mobile communications terminal apparatuses of a W-CDMA (Wideband-CDMA) system.
In communication terminal apparatuses including the mobile communications terminal apparatus, in order to generate a transmission wave, the electric power amplification circuit (also referred to as power amplifier, particularly transmission power amplifying circuit) is provided (see Japanese Unexamined Patent Application Publication No. H11-261479, for example). This electric power amplification circuit is arranged such that the frequency band corresponds to a frequency band of the transmission wave.
On the other hand, as the demand for the mobile communications terminal apparatuses increases and the number of applications for terminal apparatus increases, carrier frequencies are to be reorganized in order to increase information communicating capability of mobile communications.
As the mobile communications carrier frequencies are reorganized, it is necessary for each terminal apparatus to install a system corresponding to a new frequency. Further, due to the influence of the increasing applications, the terminals increase in size. The miniaturization of the inner components of the terminal apparatus is required to prevent the size from increasing.
For this reason, the recent trend of power amplifiers of manufactures is mainly to perform miniaturization. Consequently, the manufactures work on the development of a size reduction of the power amplifier corresponding to each frequency to be reorganized.